Pathogens ‘lurking’ in Lao PDR’s wildlife markets can lead to emergence of zoonotic diseases

Study found that several mammals being sold at the markets have been previously documented to host pathogens that can cause zoonotic diseases like Ebola, Hendra, Rabies, and SARS.

Biosafety standards at the wildlife markets were poor, the researchers write, increasing the opportunities for the transmission of pathogens from wildlife to humans.

Many of the animals being sold at Lao PDR’s wildlife markets are also threatened with extinction, the study found.

Conditions at wildlife markets in LaoPeople’s Democratic Republic (Lao PDR) could lead to public health “catastrophes”, a new study warns.

Poor biosafety standards and high volume of wild animals illegally sold at wildlife markets in Lao PDR present a high risk for the emergence of SARS-like zoonotic diseases, researchers write in the study published in PLoS ONE.

“Human disease-causing pathogens clearly lurk in wildlife markets,” co-author Sarah Olson of WCS’s Wildlife Health & Health Policy Program, said in a statement. “The danger to your health is just less visible than the dangers to conservation. You can usually observe endangered species illegally on sale, but a range of largely invisible pathogens are likely there as well.”

At these markets, the team observed more than 6,600 animals — both alive and dead — for sale. These included nearly 2,000 mammals, over 3,000 birds and about 1,500 reptiles. On average, the traders sold about 22 to 931 wild animals per day in these markets.

The team found that several mammals being sold have been previously documented to host 36 pathogens that can cause zoonotic diseases. These pathogens include viruses associated with Ebola, Hendra, Lassa fever, Rabies, and SARS, as well as bacteria associated with leptospirosis and Mycobaterium tuberculosis.

Biosafety standards at these markets were poor, the researchers write. This increases the opportunities for the transmission of pathogens from wildlife to humans, they add.

For example, only four of the seven markets had running water. The team also observed that most butchers did not clean their instruments, worked from dirty work tables, and did not wash their hands. Wild animals at these markets were also frequently in contact with other fresh produce, including vegetables, increasing the risk of cross contamination. Moreover, the markets are located in towns or on major roads frequented by foreigners, the authors note, which poses a risk for the spread of diseases both nationally and internationally.

“As veterinarians we have responsibilities for ensuring the public’s health,” Watthana Theppangna, co-author and Head of the PREDICT partner Bio-Safety Level III Laboratory at the Lao PDR National Animal Health Laboratory, said in the statement. “We are worried about the presence of wildlife in markets and the potential for pathogens to spread to people through the wildlife trade.”

Study found several threatened species for sale in Lao PDR’s wildlife markets, such as the critically endangered Vietnamese pond turtle. Photo by Fredlyfish4, Wikimedia Commons, CC By-SA 3.0.

Many of the animals being sold at Lao PDR’s wildlife markets are also threatened with extinction, the study found.

Between 2010 to 2013, the team made 375 visits to 93 wildlife markets, and found that nearly 6,500 animals were classified as near extinct or threatened with extinction under the Lao PDR Wildlife and Aquatic Law.

Additionally, 238 animals from 30 species being sold at the markets were classified as threatened under the IUCN Red List Criteria. These include critically endangered species like the Vietnamese pond turtle (Mauremys annamensis), and endangered species such as the yellow-headed temple turtle (Hieremys annandalii), keeled box turtle (Pyxidea mouhotii), elongated tortoise (Indotestudo elongate), big-headed turtle (Platysternon megacephalum), Asian elephant (Elephas maximus), and Loatian rock rat (Laonastes aenigmamus).

In fact, endangered turtles, tortoises, deer and lorises made the bulk of endangered animals being sold at the markets. This suggests that wildlife is targeted more at affluent urban consumers, rather than for subsistence consumption, the authors write.

Moreover, wildlife was usually sold openly at the markets, the team found, highlighting the lack of law enforcement.

“Although enforcement efforts are being made by the Government of Lao PDR to curb the illegal trade in wildlife, the government needs more support to raise capacity to conduct investigations and prosecutions of wildlife traders,” Soubanh Silithammavong, co-author and PREDICT Country Coordinator in Lao PDR said. “This study should help raise awareness of the serious threat that wildlife trade in Lao PDR poses to both biodiversity and human health.”